Revisiting the Extensor Hallucis Longus Tendon: Anatomical Classification and Orthopedic Implications

Background: Anatomical variations of the extensor hallucis longus (EHL) tendon hold significant implications for foot and ankle surgery, yet they remain underrepresented in orthopedic literature. Accurate recognition of these variants is crucial for minimizing iatrogenic injuries and improving surgical outcomes. Aim: This narrative review aims to summarize current anatomical knowledge on EHL tendon morphology, with a particular focus on the classification system proposed by Olewnik et al. Emphasis is placed on its diagnostic, radiological, and surgical relevance. Methods: A comprehensive literature review was conducted, integrating findings from cadaveric dissections, imaging studies, and clinical observations. The Olewnik classification-based on the number and insertion of EHL tendon slips-serves as the organizing framework for the anatomical and surgical discussion. Findings: The Olewnik classification delineates three primary types: Type I (single slip), Type II (two slips, subdivided into IIa-IIc), and Type III (three slips). Each type is discussed in terms of anatomical features, diagnostic challenges on MRI and ultrasound, and implications for surgical exposure, tendon transfer, and graft harvesting. Comparative analysis with prior typologies underscores the enhanced clinical utility of the Olewnik system. Conclusions: The reviewed classification offers a reproducible, imaging-compatible, and surgically applicable framework for understanding EHL tendon variability. Incorporating this system into preoperative planning may enhance procedural safety and precision. Further clinical validation and broader integration into surgical education are warranted.